It means he is normal. When puberty starts for young boys there is often overwhelming curiosity about the opposite sex. Some boys go to on line pornography, magazines, and some simply seek out what is available at home. I would discuss this with him. He should not be taking his sister's clothes, but I would acknowledge his emerging sexuality. I would also find out what his school's health education curriculum is concerning these topics. All too often schools are behind the growth and do not deal with sexual issues until several grades later.
Wayne Yankus, MD, FAAP
expert panelist: pediatrics